Remove more GpuMemoryBufferId plumbing

content/browser/renderer_host/render_widget_host_view_mac.mm

Index: content/browser/renderer_host/render_widget_host_view_mac.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 6be3c4252eab9f9a0f1de0c8d8f10df5ad09afe5..3988f1fa6ef9c923322d845418415ff959301997 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -405,11 +405,6 @@ float FlipYFromRectToScreen(float y, float rect_height) {
 ////////////////////////////////////////////////////////////////////////////////
 // DelegatedFrameHost, public:
 
-int RenderWidgetHostViewMac::DelegatedFrameHostGetGpuMemoryBufferClientId()
-    const {
-  return render_widget_host_->GetProcess()->GetID();
-}
-
 ui::Layer* RenderWidgetHostViewMac::DelegatedFrameHostGetLayer() const {
   return browser_compositor_->GetRootLayer();
 }